1. Field
Embodiments of the present disclosure relate to an electric brake system, and more particularly, to an electric brake system capable of stably performing a braking operation even when a simulation valve operates abnormally.
2. Description of the Related Art
A brake system for braking is necessarily mounted on a vehicle, and a variety of systems for providing stronger and more stable braking have been proposed recently.
For example, there are brake systems including an anti-lock brake system (ABS) for preventing a wheel from sliding while braking, a brake traction control system (BTCS) for preventing a driving wheel from slipping when a vehicle is suddenly unintendedly accelerated or intentionally accelerated, an electronic stability control system (ESC) for stably maintaining a driving state of a vehicle by combining an ABS with traction control to control a hydraulic pressure of a brake, and the like.
Such an electric brake system is designed to electronically control a flow of a braking hydraulic pressure, and is used to include a pressure source which receives a braking intent of a driver in the form of an electrical signal from a pedal displacement sensor, which senses a displacement of a brake pedal when the driver steps on the brake pedal, and then supplies a hydraulic pressure to a wheel cylinder.
Also, the electric brake system includes a simulation device capable of providing a driver with a reaction force according to a pedal effort of the brake pedal. At this point, the simulation device is connected to a master cylinder and a reservoir, and a simulation valve is installed at an oil flow path at which the simulation device and the reservoir are connected to each other, or at an oil flow path at which the master cylinder and the simulation device are connected to each other.
Also, when the electric brake system operates abnormally, a backup flow path for connecting the master cylinder to the wheel cylinder is provided to deliver a hydraulic pressure, which is discharged from the master cylinder, to the wheel cylinder, and a cut valve is installed at the backup flow path to control an oil flow. That is, the cut valve is closed while the electric brake system operates normally, and is open while the electric brake system operates abnormally, thereby enabling the hydraulic pressure discharged from the master cylinder to be delivered to the wheel cylinder. At this point, when the electric brake system operates abnormally, the simulation valve is provided to be closed to enable the hydraulic pressure discharged from the master cylinder to be completely delivered to the wheel cylinder such that stable braking may be performed.
However, when a problem occurs at the simulation valve while the electric brake system operates normally, for example, when a high pressure is formed for a short time while rapid braking is performed, or when the simulation valve is adhered and fixed or an electromagnetic force is insufficiently applied to the simulation valve, the simulation valve is provided in a closed state. Therefore, oil inside the simulation device is not delivered to the reservoir according to a brake pedal force and thus the brake pedal does not move so that there occurs a problem in which a braking operation may not be performed.